Is it possible to mimic nuts and bolts in blender using Normal maps?
This video shows how to sort out normal maps to paint "bump".  If you use a an alpha brush/stencil you could paint "bump" bolts etc using texture paint, adding an extra "bump layer" (video etc). If you can find the free IK-brush kit for blender that's free online somewhere, it has bolts/screws heads etc in the brushes.  It may be wise to look up "normal map painting with alpha brushes" also.

https://youtu.be/svzKoq3vew0